In popular music, audio sources are frequently reproduced in reverse as part of a passage in a musical piece. This effect is typically achieved by recording an audio source onto magnetic tape and then playing the tape backwards on a special tape recorder. The sound of an audio source reproduced in reverse, such as a human voice, produces an interesting and often pleasing effect within a musical piece.
More recently the effect has been achieved, particularly in rap-style music, by playing a phonograph record backwards. This is accomplished by playing a phonograph record in its normal counter clockwise direction and, when the effect is desired, grasping the record and pushing it in a clockwise rotation momentarily so that the phonograph needle reproduces the recorded signal in reverse. This technique is commonly known as "scratching", presumably due to the type of sound produced, and is frequently used in rap-style music.
The effect of playing a sound sample in reverse cannot be accomplished in real time with the existence of the original sound source because a sound sample must first be recorded in its entirety before the sample can be reproduced in reverse. A sound cannot be reproduced, in forward or reverse, before it exists.
Further, since the advent of compact disc technology, phonograph records are becoming increasing less common. Accordingly, the availability of LP records for performing "scratching" is becoming a problem.
Therefore, it is an object of the present invention to provide a back-masking effect generator which simulates the sound of playing an input audio source in reverse almost in real time.
It is another object of the present invention to provide a back-masking effect generator which can simulate the sound of "scratching".
It is a further object of the present invention to provide a back-masking effect generator which can be used in live performances without the need for a prerecorded audio signal.